1. Field of the Invention
The present invention relates to a mobile telephone communication system. More particularly, it relates to a mobile telephone communication system for performing communication with a group constituted of plural mobile telephones.
2. Description of Prior Art
Recently, the demands for the mobile telephone have been known and the situations in using the mobile telephones have been diversified. Accordingly, it is required to provide a communication system, which can meet these demands and situations.
In the case where the public telephone network can not be used, for example, in a search for a mountaineering disaster, rescue operation and operation for collecting data on a fire scene, and the like, there are situations where the mobile telephone is used for contact and report.
In these cases, many people have mobile telephones and rescue operations and operations for collecting data, and the like, are performed by a group of people. Further, as special characteristics, there are some cases where the group operates in an area which is not very large and all of the constituent members move to the same area as a group.
Some mobile telephones owned by the group are usually allocated one subscriber number to one subscriber. Accordingly, it is required to perform a calling to any one of the mobile telephones owned by the subscribers who are constituent members, even if a calling is made to contact and notify the group.
However, when a called subscriber is busy, it is impossible for the subscriber to receive the call. Accordingly, it becomes difficult to contact and notify the group. More particularly, it becomes extremely important to receive the call effectively, in a case demanding immediate attention, for example, a rescue operation, operation for collecting data, and the like.
It is also inefficient to repeat the call sequentially until it becomes possible to be received by a mobile telephone held by any one of the subscribers who are constituent members of the group, from the view point of efficiency and immediate attention.